fdt: Add Python bindings
An early version of this is available upstream. Bring it in as a starting
point. This is from dtc upstream commit e56f2b0.
Future work will plumb it into dtoc and remove the now-unnecessary local
libraries.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/libfdt/pylibfdt/libfdt.i b/lib/libfdt/pylibfdt/libfdt.i
new file mode 100644
index 0000000..3b11bb0
--- /dev/null
+++ b/lib/libfdt/pylibfdt/libfdt.i
@@ -0,0 +1,389 @@
+/*
+ * pylibfdt - Flat Device Tree manipulation in Python
+ * Copyright (C) 2017 Google, Inc.
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0+ BSD-2-Clause
+ */
+
+%module libfdt
+
+%{
+#define SWIG_FILE_WITH_INIT
+#include "libfdt.h"
+%}
+
+%pythoncode %{
+
+import struct
+
+# Error codes, corresponding to FDT_ERR_... in libfdt.h
+(NOTFOUND,
+ EXISTS,
+ NOSPACE,
+ BADOFFSET,
+ BADPATH,
+ BADPHANDLE,
+ BADSTATE,
+ TRUNCATED,
+ BADMAGIC,
+ BADVERSION,
+ BADSTRUCTURE,
+ BADLAYOUT,
+ INTERNAL,
+ BADNCELLS,
+ BADVALUE,
+ BADOVERLAY,
+ NOPHANDLES) = QUIET_ALL = range(1, 18)
+# QUIET_ALL can be passed as the 'quiet' parameter to avoid exceptions
+# altogether. All # functions passed this value will return an error instead
+# of raising an exception.
+
+# Pass this as the 'quiet' parameter to return -ENOTFOUND on NOTFOUND errors,
+# instead of raising an exception.
+QUIET_NOTFOUND = (NOTFOUND,)
+
+
+class FdtException(Exception):
+ """An exception caused by an error such as one of the codes above"""
+ def __init__(self, err):
+ self.err = err
+
+ def __str__(self):
+ return 'pylibfdt error %d: %s' % (self.err, fdt_strerror(self.err))
+
+def strerror(fdt_err):
+ """Get the string for an error number
+
+ Args:
+ fdt_err: Error number (-ve)
+
+ Returns:
+ String containing the associated error
+ """
+ return fdt_strerror(fdt_err)
+
+def check_err(val, quiet=()):
+ """Raise an error if the return value is -ve
+
+ This is used to check for errors returned by libfdt C functions.
+
+ Args:
+ val: Return value from a libfdt function
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ val if val >= 0
+
+ Raises
+ FdtException if val < 0
+ """
+ if val < 0:
+ if -val not in quiet:
+ raise FdtException(val)
+ return val
+
+def check_err_null(val, quiet=()):
+ """Raise an error if the return value is NULL
+
+ This is used to check for a NULL return value from certain libfdt C
+ functions
+
+ Args:
+ val: Return value from a libfdt function
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ val if val is a list, None if not
+
+ Raises
+ FdtException if val indicates an error was reported and the error
+ is not in @quiet.
+ """
+ # Normally a list is returned which contains the data and its length.
+ # If we get just an integer error code, it means the function failed.
+ if not isinstance(val, list):
+ if -val not in quiet:
+ raise FdtException(val)
+ return val
+
+class Fdt:
+ """Device tree class, supporting all operations
+
+ The Fdt object is created is created from a device tree binary file,
+ e.g. with something like:
+
+ fdt = Fdt(open("filename.dtb").read())
+
+ Operations can then be performed using the methods in this class. Each
+ method xxx(args...) corresponds to a libfdt function fdt_xxx(fdt, args...).
+
+ All methods raise an FdtException if an error occurs. To avoid this
+ behaviour a 'quiet' parameter is provided for some functions. This
+ defaults to empty, but you can pass a list of errors that you expect.
+ If one of these errors occurs, the function will return an error number
+ (e.g. -NOTFOUND).
+ """
+ def __init__(self, data):
+ self._fdt = bytearray(data)
+ check_err(fdt_check_header(self._fdt));
+
+ def path_offset(self, path, quiet=()):
+ """Get the offset for a given path
+
+ Args:
+ path: Path to the required node, e.g. '/node@3/subnode@1'
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ Node offset
+
+ Raises
+ FdtException if the path is not valid or not found
+ """
+ return check_err(fdt_path_offset(self._fdt, path), quiet)
+
+ def first_property_offset(self, nodeoffset, quiet=()):
+ """Get the offset of the first property in a node offset
+
+ Args:
+ nodeoffset: Offset to the node to check
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ Offset of the first property
+
+ Raises
+ FdtException if the associated node has no properties, or some
+ other error occurred
+ """
+ return check_err(fdt_first_property_offset(self._fdt, nodeoffset),
+ quiet)
+
+ def next_property_offset(self, prop_offset, quiet=()):
+ """Get the next property in a node
+
+ Args:
+ prop_offset: Offset of the previous property
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ Offset of the next property
+
+ Raises:
+ FdtException if the associated node has no more properties, or
+ some other error occurred
+ """
+ return check_err(fdt_next_property_offset(self._fdt, prop_offset),
+ quiet)
+
+ def get_name(self, nodeoffset):
+ """Get the name of a node
+
+ Args:
+ nodeoffset: Offset of node to check
+
+ Returns:
+ Node name
+
+ Raises:
+ FdtException on error (e.g. nodeoffset is invalid)
+ """
+ return check_err_null(fdt_get_name(self._fdt, nodeoffset))[0]
+
+ def get_property_by_offset(self, prop_offset, quiet=()):
+ """Obtains a property that can be examined
+
+ Args:
+ prop_offset: Offset of property (e.g. from first_property_offset())
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ Property object, or None if not found
+
+ Raises:
+ FdtException on error (e.g. invalid prop_offset or device
+ tree format)
+ """
+ pdata = check_err_null(
+ fdt_get_property_by_offset(self._fdt, prop_offset), quiet)
+ if isinstance(pdata, (int)):
+ return pdata
+ return Property(pdata[0], pdata[1])
+
+ def first_subnode(self, nodeoffset, quiet=()):
+ """Find the first subnode of a parent node
+
+ Args:
+ nodeoffset: Node offset of parent node
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ The offset of the first subnode, if any
+
+ Raises:
+ FdtException if no subnode found or other error occurs
+ """
+ return check_err(fdt_first_subnode(self._fdt, nodeoffset), quiet)
+
+ def next_subnode(self, nodeoffset, quiet=()):
+ """Find the next subnode
+
+ Args:
+ nodeoffset: Node offset of previous subnode
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ The offset of the next subnode, if any
+
+ Raises:
+ FdtException if no more subnode found or other error occurs
+ """
+ return check_err(fdt_next_subnode(self._fdt, nodeoffset), quiet)
+
+ def totalsize(self):
+ """Return the total size of the device tree
+
+ Returns:
+ Total tree size in bytes
+ """
+ return check_err(fdt_totalsize(self._fdt))
+
+ def off_dt_struct(self):
+ """Return the start of the device tree struct area
+
+ Returns:
+ Start offset of struct area
+ """
+ return check_err(fdt_off_dt_struct(self._fdt))
+
+ def pack(self, quiet=()):
+ """Pack the device tree to remove unused space
+
+ This adjusts the tree in place.
+
+ Args:
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Raises:
+ FdtException if any error occurs
+ """
+ return check_err(fdt_pack(self._fdt), quiet)
+
+ def delprop(self, nodeoffset, prop_name):
+ """Delete a property from a node
+
+ Args:
+ nodeoffset: Node offset containing property to delete
+ prop_name: Name of property to delete
+
+ Raises:
+ FdtError if the property does not exist, or another error occurs
+ """
+ return check_err(fdt_delprop(self._fdt, nodeoffset, prop_name))
+
+ def getprop(self, nodeoffset, prop_name, quiet=()):
+ """Get a property from a node
+
+ Args:
+ nodeoffset: Node offset containing property to get
+ prop_name: Name of property to get
+ quiet: Errors to ignore (empty to raise on all errors)
+
+ Returns:
+ Value of property as a bytearray, or -ve error number
+
+ Raises:
+ FdtError if any error occurs (e.g. the property is not found)
+ """
+ pdata = check_err_null(fdt_getprop(self._fdt, nodeoffset, prop_name),
+ quiet)
+ if isinstance(pdata, (int)):
+ return pdata
+ return bytearray(pdata[0])
+
+
+class Property:
+ """Holds a device tree property name and value.
+
+ This holds a copy of a property taken from the device tree. It does not
+ reference the device tree, so if anything changes in the device tree,
+ a Property object will remain valid.
+
+ Properties:
+ name: Property name
+ value: Proper value as a bytearray
+ """
+ def __init__(self, name, value):
+ self.name = name
+ self.value = value
+%}
+
+%rename(fdt_property) fdt_property_func;
+
+typedef int fdt32_t;
+
+%include "libfdt/fdt.h"
+
+%include "typemaps.i"
+
+/* Most functions don't change the device tree, so use a const void * */
+%typemap(in) (const void *)(const void *fdt) {
+ if (!PyByteArray_Check($input)) {
+ SWIG_exception_fail(SWIG_TypeError, "in method '" "$symname"
+ "', argument " "$argnum"" of type '" "$type""'");
+ }
+ $1 = (void *)PyByteArray_AsString($input);
+ fdt = $1;
+ fdt = fdt; /* avoid unused variable warning */
+}
+
+/* Some functions do change the device tree, so use void * */
+%typemap(in) (void *)(const void *fdt) {
+ if (!PyByteArray_Check($input)) {
+ SWIG_exception_fail(SWIG_TypeError, "in method '" "$symname"
+ "', argument " "$argnum"" of type '" "$type""'");
+ }
+ $1 = PyByteArray_AsString($input);
+ fdt = $1;
+ fdt = fdt; /* avoid unused variable warning */
+}
+
+%typemap(out) (struct fdt_property *) {
+ PyObject *buff;
+
+ if ($1) {
+ resultobj = PyString_FromString(
+ fdt_string(fdt1, fdt32_to_cpu($1->nameoff)));
+ buff = PyByteArray_FromStringAndSize(
+ (const char *)($1 + 1), fdt32_to_cpu($1->len));
+ resultobj = SWIG_Python_AppendOutput(resultobj, buff);
+ }
+}
+
+%apply int *OUTPUT { int *lenp };
+
+/* typemap used for fdt_getprop() */
+%typemap(out) (const void *) {
+ if (!$1)
+ $result = Py_None;
+ else
+ $result = Py_BuildValue("s#", $1, *arg4);
+}
+
+/* We have both struct fdt_property and a function fdt_property() */
+%warnfilter(302) fdt_property;
+
+/* These are macros in the header so have to be redefined here */
+int fdt_magic(const void *fdt);
+int fdt_totalsize(const void *fdt);
+int fdt_off_dt_struct(const void *fdt);
+int fdt_off_dt_strings(const void *fdt);
+int fdt_off_mem_rsvmap(const void *fdt);
+int fdt_version(const void *fdt);
+int fdt_last_comp_version(const void *fdt);
+int fdt_boot_cpuid_phys(const void *fdt);
+int fdt_size_dt_strings(const void *fdt);
+int fdt_size_dt_struct(const void *fdt);
+
+%include <../libfdt/libfdt.h>